Steareth-15 is a polyethylene glycol ether of stearyl alcohol, functioning primarily as a nonionic surfactant and emulsifier in cosmetic formulations [1]. It is synthesized through the ethoxylation of stearyl alcohol, a process that involves reacting stearyl alcohol with ethylene oxide [2]. The number "15" in its name indicates the average number of ethylene oxide units added to the stearyl alcohol molecule [1].
The production of steareth-15 begins with obtaining stearyl alcohol, typically derived from vegetable oils or animal fats via reduction of stearic acid [3]. This stearyl alcohol is then reacted with ethylene oxide under controlled conditions, usually in the presence of a catalyst such as sodium hydroxide or potassium hydroxide [3]. The reaction is carefully monitored to ensure the desired degree of ethoxylation, yielding steareth-15 with consistent properties [3]. Post-reaction, the product undergoes purification processes, including neutralization and removal of any unreacted materials, to ensure its quality and suitability for cosmetic applications [3].
Steareth-15 is valued for its emulsifying properties, facilitating the blending of oil and water-based ingredients in cosmetic formulations, and it helps to stabilize emulsions, preventing separation and ensuring a homogenous mixture [4]. As a surfactant, it lowers the surface tension between liquids, allowing for better dispersion and cleansing properties in products like cleansers and shampoos [4]. Additionally, steareth-15 can act as a solubilizer for fragrances and oils, enhancing the overall aesthetics and functionality of cosmetic products [4].
Steareth-15 is used across a wide range of cosmetic and personal care products, including creams, lotions, cleansers, and hair care items [5]. In creams and lotions, it helps to create stable, smooth emulsions that provide a pleasant skin feel [5]. In cleansers and shampoos, it aids in the removal of dirt and oil from the skin and hair [5]. Its mildness and non-irritating properties make it suitable for formulations designed for sensitive skin [5].
Steareth-15 is typically packaged in multi-layer paper bags with polyethylene liners or in fiber drums to protect it from moisture and contamination [6]. Transportation should occur in dry, clean vehicles, and it should be stored in a cool, dry, and well-ventilated area [6]. Avoid exposure to extreme temperatures and direct sunlight during both transportation and storage to maintain its stability and prevent degradation [6].
Citations:
[1] International Cosmetic Ingredient Dictionary & Handbook. (n.d.). Steareth-15. Personal Care Products Council.
[2] Schmolka, I. R. (1991). Nonionic Surfactants: Chemical Analysis. CRC Press.
[3] Hill, K. (Ed.). (2000). Alkoxylated Surfactants. Marcel Dekker.
[4] Draelos, Z. D. (2018). Cosmetic Dermatology: Products and Procedures. John Wiley & Sons.
[5] Lodén, M., & Wessman, W. (2001). Dry Skin and Moisturizers: Chemistry and Function. CRC Press.
[6] Flick, E. W. (1991). Cosmetic and Toiletry Formulations, Vol. 3. Noyes Publications.
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